The time, along with position and velocity, is used in the calculation of a
parameter called the range gate which is used in track while scan radar
systems to tell the radar where to expect (correlate) a radar return for a
tracked object. Clock drift can cause the gate to drift away from the
actual radar return's location, once the difference gets past a certain
threshold the radar return and track will decorrelate and the radar will
loose (or drop) the track.

The actual details of how this occurred on the day are a little more
complex, if you're interested see the case study at the link for more
detail http://wp.me/ax0Kp-2tK.

On Tue, May 5, 2015 at 6:56 PM, Martyn Thomas <
martyn_at_xxxxxx

> Why did they need to keep the time, over a period of 100 hours, in order> to determine how far away an incoming missile is? The two things appear to> me to be unrelated.>> Martyn>> On 04/05/2015 21:57, Steve Tockey wrote:>>> Can static analysis catch this kind of defect:>> https://www.ima.umn.edu/~arnold/disasters/patriot.html>>>> _______________________________________________> The System Safety Mailing List> systemsafety_at_xxxxxx
>>